An electrophysiology mapping system utilizes multiple surface electrodes on a body of a patient for visualization of internal bodily structures, and especially cardiac structures. Some such systems can further utilize a magnetic field source adjacent to the patient for internal bodily structure visualization. In place of an intra-cardiac electrode or other intra-cardiac sensor, an echo probe is utilized external to the body. The electrode or other sensor on the echo probe is spaced a known distance from a sound wave detector, such as a piezoelectric crystal which also generates sound waves, the sensor assisting in correlating echo probe sensed patient structural data with patient structural data otherwise gathered by the EP mapping system. This data is integrated together for visualization on the EP mapping display without requiring an intra-cardiac electrode or other intra-cardiac sensor.
